Cross-border NTFP value chains Laos – China - nafri

Results obtained from studying the relationship between tree size and resin production
demonstrate that small trees are likely to produce less benzoin than larger trees. Trees
having a dbh less than 13 cm were found to be unsuitable for tapping. There was no
direct comparison of the resin yield in relation to bark thickness of the tree. However,
given that bark thickness is correlated positively with tree diameter, it would be
reasonable to assume that trees with thick bark are likely to produce more benzoin than
those with thin bark. The results, however, did not support the popular claim by villagers
that benzoin yield is greater at higher tapping positions on the tree. The tapping results,
however, do confirm that more benzoin is produced at higher (but not the highest)
positions on the stem. But the results raise more questions than answers. It was
expected that the lower portion of the stem would produce more benzoin because the
diameter is larger, and bark is thicker and rougher than the upper portion. This aspect of
benzoin production is worthy of further investigation. In addition, it is also recommended
to conduct further studies as the overall productivity of the trees in the experimental
plots was extremely poor when compared to that observed for the trees tapped by
villagers in adjacent areas.
The tapping experiments demonstrated clear differences among the 3 tapping methods.
All 3 methods showed satisfactory results in terms of resin production with the
traditional Lao method as the most suitable one. However, it was not possible, to
determine the optimal tapping method among them as other factors, such as the time
required to tap and ease of application, were not assessed. It is recommended that
testing of the Indonesian, V-shaped and Lao A methods be repeated, taking into
account such factors. Also, if sustainable yield from styrax trees is to be achieved, it is
necessary to study the optimal number of tapping cuts per tree which do not cause
serious harm to the trees and yet assure that tapping can continue for successive
seasons.
The orientation aspect of the tapping cuts on the tree may influence yield, due to the
effects of sunlight and leafiness of the tree. One side of the tree may be leafier than
another and the exposure down-slope may be different from the exposure up-slope.
These site factors of individual trees may influence their resin production and should be
examined in any further trials.
In the trials, it was also observed that cutting of the undergrowth vegetation below the
styrax trees may reduced overall resin yield as the tapping cuts dry out because of
exposure to direct sunlight and heat. However, the trial data of both years (1999 and
2000) did not support the assumption that undergrowth has a significant influence on
the capacity of trees to exude benzoin. The differences between individual trees might
be more important.
Trying to stimulate sap flow by beating the bark around the tapping cut has no
significant influence on the benzoin production.
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